Ian,

I have not (yet, anyway) come across a Waste Oil Burner during my travels/shopping. Do you know the Brand Name of any?
I went to see one of those "Fonta" Boilers today. ( See my earlier posting)It can burn anything almost (including coal, so no Government Grant to offset cost)
It certainly looks and seems to operate, very well. The people who have it installed told me that they need to fuel it up twice a day for continuous running. They burn Logs and/ or Wood Scraps/Offcuts.
Kiln dried wood is particularly suitable as it burns completely as heat for the water boiler. Wet timber can be burned but is , consequently, inefficient( in the ratio of its moisture content.) Size of logs or pieces is, preferably, about 7" x 5" x 5"
The model that they have installed is a 30Kw which is about 5' H x 2' W x 5' L. It cost them 3,000Euro but they did have to buy a Stove Pipe of some 9" diameter (critical - they said) for a further 500Euro.
Their burner is set up in a shed which is then incidentally heated by it.
There is a valve on the output pipe that sends some 30% of heated water directly back to the boiler thus saving energy.
The fuelling is carried out much as one would fuel and fire up a normal living room fire- in- a -grate , with paper, small sticks and then logs, once fired (Improved draughting is available by a "choke" arrangement on the firebox) the fuel requires to be topped up approx every 12 hrs. The temperature is electronically controlled at 70 - 73 Degrees Farenheit. (They told me that , without electricity it can be kept burning but requires continual supervision.)
In this site the boiler a) heats Domestic Water and b) heats up to 10 radiators in a house some 10/12 ft away from the shed. It is also (as I mentioned) heating the Boiler- room of the Out-house as well as an office, toilet and utility room in the same Out-building.
The owners have had Oil fired Central Heating for many years and also an Oil Fired Rayburn Cooker both of which they have kept as a stand-by system. This is still connected to the house plumbing with non-return valves to control the flow of hot water depending on which system is operating.
In the back yard of this persons house I could readily observe a pile of small trees ready for chain-sawing and outside the shed door there was a farm bucket of ashes which, I was informed, was actually three weeks clean out of the firebox, after continuous operation. Naturally the burner would need to be cleaned of deposits (resin, soot, whatever) after a Winter of full-time burning (As Oil-Fired Burners do also)
I have to say that, as an ordinary consumer searching for a heating solution, it was impressive. It is (Patented) and Manufactured by IRLEH, Wolsztyn (Is this Poland ?) and the "Fona" name is (probably) just used here (Ireland) for sales purposes.